In manufacturing a semiconductor device, a metal film disposed on a semiconductor substrate is often patterned. As a typical patterning method, wet etching is performed with a resist layer used as a mask. The resist layer is generally formed by applying, exposing, and developing a photoresist.
In storing the photoresist before use and the resist layer before exposure, particular care has been taken conventionally. For example, according to Japanese Patent Application Laid-Open No. 5-323589, a photosensitive resin composition which is excellent in preservation stability is proposed. According to this document, it is suggested that when the photosensitive resin composition is formed into a dry film and stored in an unexposed state, the dry film can be prevented from being exposed to light for a long period of time.